FFMPEG is required in order to provide all the features.
If this is missing, video conversion will not be supported (the users will
be able to upload only mp4 video files ".mp4");

2 Install ffmpeg
------------------
You need a ffmpeg newer than revision 10703 compiled with lib264 and
libfdk_aac or libfaac support. Also make sure that the ffmpeg executable is in
your PATH.
Since there is now current ffmpeg version in any of the linux repositories
(as of October 2015), the only possibility is to compile from source (libx264,
libfdk_aac and ffmpeg).
